Many of the animated images on this website use the GIF™ (Graphics Interchange Format) standard, which was developed by CompuServe for the storage and transmission of raster-based graphics information and launched as version 87a was released in 1987 and version 89a in 1989.

The format supports up to 8 bits per pixel for each image, allowing a single image to reference its own palette of up to 256 different colours chosen from the 24-bit RGB colour space. It also supports animations and allows a separate palette of up to 256 colours for each frame. These palette limitations make GIF less suitable for reproducing colour photographs and other images with colour gradients, but suited for simpler images such as graphics or logos with solid areas of colour. GIF™ images are compressed using the LZW (Lempel–Ziv–Welch) lossless data compression technique to reduce the file size without degrading the visual quality.

Although the Graphics Interchange Format was not designed as an animation medium, its ability to store multiple images in one file naturally suggested using the format to store the frames of an animation sequence. This feature, together with the included control data, makes it easy to produce simple animations and is used extensively on the Web. By default, an animation displays the sequence of frames only once, stopping when the last frame is displayed. To enable an animation to loop, a block was added in 1995 by Netscape. This allowed the number of times a sequence of frames should be played to be specified, or to be repeated continuously.

The size and colour quality of animated GIF™ files can vary significantly depending on the application used to create them. Strategies for minimizing file size include using a common global colour table for all frames, rather than a complete local colour table for each frame and minimizing the number of pixels covered in successive frames, so that only the pixels that change from one frame to the next are included in the successive frame. Not optimising a series of independent frame images into a composite animation results in a large file size.